The invention relates to a process and a device for scavenging a metal melt, in particular of steel, in a casting ladle or the like, which has an outlet at the bottom having a plug closing from the inside of the ladle whereby the scavenging gas, for example, argon is introduced through the bottom of the ladle in the melting bath.
It is known to scavenge metal melts by means of a gas introduced in the melting bath to purify or homogenize the bath and to bring the bath up to the most possible uniform temperature. In steel production, argon is mostly used as a scavenging gas which is introduced in the casting ladle, preferably, through the bottom of the ladle. The known casting ladles have a scavenging gas supply line at the bottom of the ladle for this purpose in addition to their outlet which can, for example, be closed by a plug arranged on a plug rod. This supply line consists of a porous sheet metal-clad conical gas scavenging stone which is inserted in a perforated fire brick arranged at the bottom of the ladle by using a joint kit and is exchangeably held by means of a bayonet lock. The scavenging stone has a threaded pipe for connecting the scavenging gas line.
The installation of scavenging stones of the above-mentioned type involves considerable expense. In use, the scavenging stone is exposed to a high degree of wear and must, therefore, be exchanged after a certain number of castings. The premature wear of the scavenging stone often leads to a undesired reduced service life of the ladle. The scavenging stone inevitably creates a hazard for steel run-out. When in one operation, only part of the melt is subjected to gas scavenging, which is often the case. In practice, casting ladles must be used side by side with built-in and without scavenging devices. When not in use, the casting ladles equipped with the scavenging device must be either kept hot or be heated again before use to the desired temperature.
Conventional scavenging methods of the known type often lead to breakdowns and waiting periods caused by melt deposits on the more or less exhausted scavenging stones. Only when these deposits, so-called bears, are melted again, the argon can arrive through the scavenging stone in the melting bath. When the deposits do not melt, which occasionally is the case, scavenging of the melt in the casting ladle cannot be accomplished.